// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/address-map.h"
#include "src/heap/heap.h"
#include "src/isolate.h"
#include "src/objects-inl.h"
#include "src/objects/heap-object-inl.h"

namespace v8 {
namespace internal {

    RootIndexMap::RootIndexMap(Isolate* isolate)
    {
        map_ = isolate->root_index_map();
        if (map_ != nullptr)
            return;
        map_ = new HeapObjectToIndexHashMap();
        for (RootIndex root_index = RootIndex::kFirstStrongOrReadOnlyRoot;
             root_index <= RootIndex::kLastStrongOrReadOnlyRoot; ++root_index) {
            Object root = isolate->root(root_index);
            if (!root->IsHeapObject())
                continue;
            // Omit root entries that can be written after initialization. They must
            // not be referenced through the root list in the snapshot.
            // Since we map the raw address of an root item to its root list index, the
            // raw address must be constant, i.e. the object must be immovable.
            if (RootsTable::IsImmortalImmovable(root_index)) {
                HeapObject heap_object = HeapObject::cast(root);
                Maybe<uint32_t> maybe_index = map_->Get(heap_object);
                uint32_t index = static_cast<uint32_t>(root_index);
                if (maybe_index.IsJust()) {
                    // Some are initialized to a previous value in the root list.
                    DCHECK_LT(maybe_index.FromJust(), index);
                } else {
                    map_->Set(heap_object, index);
                }
            }
        }
        isolate->set_root_index_map(map_);
    }

    bool RootIndexMap::Lookup(Address obj, RootIndex* out_root_list) const
    {
        return Lookup(HeapObject::cast(Object(obj)), out_root_list);
    }

} // namespace internal
} // namespace v8
